1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 * Events provide a general-purpose way to react to / subscribe to changes
4 * within U-Boot
5 *
6 * Copyright 2021 Google LLC
7 * Written by Simon Glass <sjg@chromium.org>
8 */
9
10 #ifndef __event_h
11 #define __event_h
12
13 #include <dm/ofnode_decl.h>
14
15 /**
16 * enum event_t - Types of events supported by U-Boot
17 *
18 * @EVT_DM_PRE_PROBE: Device is about to be probed
19 */
20 enum event_t {
21 EVT_NONE,
22 EVT_TEST,
23
24 /* Events related to driver model */
25 EVT_DM_POST_INIT_F,
26 EVT_DM_PRE_PROBE,
27 EVT_DM_POST_PROBE,
28 EVT_DM_PRE_REMOVE,
29 EVT_DM_POST_REMOVE,
30
31 /* Init hooks */
32 EVT_MISC_INIT_F,
33
34 /* Device tree fixups before booting */
35 EVT_FT_FIXUP,
36
37 /* To be called once, before calling main_loop() */
38 EVT_MAIN_LOOP,
39
40 EVT_COUNT
41 };
42
43 union event_data {
44 /**
45 * struct event_data_test - test data
46 *
47 * @signal: A value to update the state with
48 */
49 struct event_data_test {
50 int signal;
51 } test;
52
53 /**
54 * struct event_dm - driver model event
55 *
56 * @dev: Device this event relates to
57 */
58 struct event_dm {
59 struct udevice *dev;
60 } dm;
61
62 /**
63 * struct event_ft_fixup - FDT fixup before booting
64 *
65 * @tree: tree to update
66 * @images: images which are being booted
67 */
68 struct event_ft_fixup {
69 oftree tree;
70 struct bootm_headers *images;
71 } ft_fixup;
72 };
73
74 /**
75 * struct event - an event that can be sent and received
76 *
77 * @type: Event type
78 * @data: Data for this particular event
79 */
80 struct event {
81 enum event_t type;
82 union event_data data;
83 };
84
85 /** Function type for event handlers */
86 typedef int (*event_handler_t)(void *ctx, struct event *event);
87
88 /**
89 * struct evspy_info - information about an event spy
90 *
91 * @func: Function to call when the event is activated (must be first)
92 * @type: Event type
93 * @id: Event id string
94 */
95 struct evspy_info {
96 event_handler_t func;
97 enum event_t type;
98 #if CONFIG_IS_ENABLED(EVENT_DEBUG)
99 const char *id;
100 #endif
101 };
102
103 /* Declare a new event spy */
104 #if CONFIG_IS_ENABLED(EVENT_DEBUG)
105 #define _ESPY_REC(_type, _func) { _func, _type, #_func, }
106 #else
107 #define _ESPY_REC(_type, _func) { _func, _type, }
108 #endif
109
event_spy_id(struct evspy_info * spy)110 static inline const char *event_spy_id(struct evspy_info *spy)
111 {
112 #if CONFIG_IS_ENABLED(EVENT_DEBUG)
113 return spy->id;
114 #else
115 return "?";
116 #endif
117 }
118
119 /*
120 * It seems that LTO will drop list entries if it decides they are not used,
121 * although the conditions that cause this are unclear.
122 *
123 * The example found is the following:
124 *
125 * static int sandbox_misc_init_f(void *ctx, struct event *event)
126 * {
127 * return sandbox_early_getopt_check();
128 * }
129 * EVENT_SPY(EVT_MISC_INIT_F, sandbox_misc_init_f);
130 *
131 * where EVENT_SPY uses ll_entry_declare()
132 *
133 * In this case, LTO decides to drop the sandbox_misc_init_f() function
134 * (which is fine) but then drops the linker-list entry too. This means
135 * that the code no longer works, in this case sandbox no-longer checks its
136 * command-line arguments properly.
137 *
138 * Without LTO, the KEEP() command in the .lds file is enough to keep the
139 * entry around. But with LTO it seems that the entry has already been
140 * dropped before the link script is considered.
141 *
142 * The only solution I can think of is to mark linker-list entries as 'used'
143 * using an attribute. This should be safe, since we don't actually want to drop
144 * any of these. However this does slightly limit LTO's optimisation choices.
145 *
146 * Another issue has come up, only with clang: using 'static' makes it throw
147 * away the linker-list entry sometimes, e.g. with the EVT_FT_FIXUP entry in
148 * vbe_simple.c - so for now, make it global.
149 */
150 #define EVENT_SPY(_type, _func) \
151 __used ll_entry_declare(struct evspy_info, _type ## _3_ ## _func, \
152 evspy_info) = _ESPY_REC(_type, _func)
153
154 /**
155 * event_register - register a new spy
156 *
157 * @id: Spy ID
158 * @type: Event type to subscribe to
159 * @func: Function to call when the event is sent
160 * @ctx: Context to pass to the function
161 * @return 0 if OK, -ve on error
162 */
163 int event_register(const char *id, enum event_t type, event_handler_t func,
164 void *ctx);
165
166 /** event_show_spy_list( - Show a list of event spies */
167 void event_show_spy_list(void);
168
169 /**
170 * event_manual_reloc() - Relocate event handler pointers
171 *
172 * Relocate event handler pointers for all static event spies. It is called
173 * during the generic board init sequence, after relocation.
174 *
175 * Return: 0 if OK
176 */
177 int event_manual_reloc(void);
178
179 /**
180 * event_notify() - notify spies about an event
181 *
182 * It is possible to pass in union event_data here but that may not be
183 * convenient if the data is elsewhere, or is one of the members of the union.
184 * So this uses a void * for @data, with a separate @size.
185 *
186 * @type: Event type
187 * @data: Event data to be sent (e.g. union_event_data)
188 * @size: Size of data in bytes
189 * @return 0 if OK, -ve on error
190 */
191 int event_notify(enum event_t type, void *data, int size);
192
193 #if CONFIG_IS_ENABLED(EVENT)
194 /**
195 * event_notify_null() - notify spies about an event
196 *
197 * Data is NULL and the size is 0
198 *
199 * @type: Event type
200 * @return 0 if OK, -ve on error
201 */
202 int event_notify_null(enum event_t type);
203 #else
event_notify_null(enum event_t type)204 static inline int event_notify_null(enum event_t type)
205 {
206 return 0;
207 }
208 #endif
209
210 #if CONFIG_IS_ENABLED(EVENT_DYNAMIC)
211 /**
212 * event_uninit() - Clean up dynamic events
213 *
214 * This removes all dynamic event handlers
215 */
216 int event_uninit(void);
217
218 /**
219 * event_uninit() - Set up dynamic events
220 *
221 * Init a list of dynamic event handlers, so that these can be added as
222 * needed
223 */
224 int event_init(void);
225 #else
event_uninit(void)226 static inline int event_uninit(void)
227 {
228 return 0;
229 }
230
event_init(void)231 static inline int event_init(void)
232 {
233 return 0;
234 }
235 #endif
236
237 #endif
238